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Re: Tarquin Trader

At last a subject I have some knowledge of.
Traders being semi displacement do tend to roll at less than 12 knots so do planing hulls so do displacement boats. They are also extremley wet boats so are Nelsons so are Aqau Stars. Its the hull design of a semi displacement boat.
Fuel consuption is a variable figure but they are less economical than a planing hull at speed.
At 10 knots I used to do Channel Isle to Gibratlar non stop 104 hours on average and burnt a gallon a mile. At 20 knots I probably would not of made Royan.
Technically at 7 knots I had over 2000 miles range. that was with the additional tanks I had fitted from new. 1000 gall capacity.
The difference between a 575 and a 535 is not 4ft as you might expect but is only 2 ft due to the way the boats are measured.
The build quality over the years has improved no end. The value for money £ for £ feet LOA over its rivals makes it hard to justify a different boat in the same class.
I have owned three Traders during my boating career and delivered many more some of them in horrendous conditions across the bay and while I would be the first to say that they might not be perfect they are an excellant sea boat with now a good build quality and one of the few affordable long distance cruising motor boats available to day.
Would I buy another one I hope to place an order shortly for a 505 (which is only 4 ft shorter than my previous 575)
I too like the Atlantic 50 but again what a price difference.
Gludy i will pm you with my telephone number and i will be pleased to talk to you about my experiences

I agree...

...in fact the Squadron might in fact be less expensive to run at displacement speed given it is dragging less hull through the water...not a slight on any boat, just a general hydrodynamic observation.

what about...

what about an Ocean Alexander? almost brought a 52 pilothouse a few years ago.these too are semi displacement. not sure about fuel consumption, but was very good at sea, with a top speed of 22-23 knots.

Re: I agree...

Butyou are missing the point Kim.

First of all the ride at displacement speed with a planing hull is not good. Secondly you cannot say go at 13 knots, just before the hump without having major fule consumption - whereas the semi-displacment hull in this case will apparantly get as far as 18 knots before using the same as the planing hull of mine.

So the comparision just does not hold.

Balance sheet:-
Belt along crusing all day at 25 knots using 0.6 mpg with noone able to make tea, get to the toilet without hurting themselves etc
OR
Go along at 18 knots, much more comfortably still getting 0.6mpg but with the ability for everyone to enjoy the passage and have the option of going slower and saving fuel or even displacment speed with one engine and using one third of the fuel. Add to this the option for long range crusing and almost double the living accomodation - the ability to dry out and so visit many more places that can be explored and that is where I am coming from.

My logic is fairly simple here, I just want someone to show me I am wrong ...

Questions on your analysis gludy

Gludy 2 questions on that:

At say 10ish knots, is it really true a displ hull is more comfortable than a planing hull? If the whole hull is in the water I cant see why it matters much what shape it is, for a given lenght and beam. Is it just that disp or SD boats are 5 tons heavier?

If a planing hull and displ hull are the same length, why does the planing hull reach its hump speed sooner, not just a bit sooner but 13knots as opposed to 18. And if it does, isn't the planing hull better because if you push over the hump to 18kts you are then comparing 18 planing with 18 displ or semi displ, so surely the planing is more efficient on fuel?

Re: Am i going worng somewhere?

Something that's always intriuged me. Some hulls are incredibly efficient at high speed. Real high speed planing speed boats, stepped hulls etc most of hull out of water (using mine as an example, most fuel efficient at speed of 30knts), those same hulls use very little fuel at 4knts and even less at 2knts.

One of the reasons I'm happy to take long trips in a small boat with plenty of fuel onboard - either whip there at no time at 30 knts and beat weather windor, or slow way down, not 10 knts fuel guzzling, but just enough to maintain steerage and sit out the rough weather. Usually somewhere inbetween though.

Most boats can be used this way. At low speeds in rough weather, even my tiddler is quite stable as long as steerage way is on. Aren't big planing boats similar to displacement and semidisplacement hulls in this regard, other than big big displacement, and semi displacement often have stabilisers? It's speed that makes things uncomfortable underway, not necessarily hull design

Re: Questions on your analysis gludy

yes, I think you are making a mistake.

A planing hull will consume a lot of fuel just before it starts to plane - that is a very inefficient speed to travel at - get over the hump and start to plane and many have a very flat fuel consumption and so consume as much at 18 knots as they do at 25 knots. This varies but what you never do with a planing boat is stay at just before hump speed.

The keel and shape of the semi displacment hull are far more comfortable at 10 knots than a planing hull.

The semi-displacment hull will increase fuel consumption above hull speed yes but it can, say, have the same fuel consumption at 18 knots that my boat has at 25 knots, so in the higher speed the planing is more efficient, no doubt but it does not offer the flexibility or comfort of the semi-displacment hull.

I would sacrifice 7 knots of cruising speed in return for far more comfort., or if I want to sacrifice more, then I would also save fuel and add to comfort.
If I wanted to go a long way, I could treble my mpg.